[libc] add guard for file pieces of printf

[michaelrj]

Summary

In the printf_core CMake, the file pieces are defined as object
libraries that depend on the File data structure. If these are added
unconditionally they'll try to evaluate that dependancy even when there
is no File available. This patch adds a guard to prevent that error.

[michaelrj]

I'm fairly sure that this will fix the arm32 bot failures, but I'm waiting for my test to come back before I push it.

[michaelrj]

This new version passes on arm32. There was a minor failure caused by type issues in parser_test.cpp that's also being fixed.

libc/src/stdio/printf_core/CMakeLists.txt

add_object_library(
   HDRS
     string_writer.h
   DEPENDS
     libc.src.string.memory_utils.memcpy_implementation
     .core_structs
 )
 
 add_object_library(
-  file_writer
-  SRCS
-    file_writer.cpp
-  HDRS
-    file_writer.h
-  DEPENDS
-    libc.src.__support.File.file
-    .core_structs
-)
-
-add_object_library(
   writer
   SRCS
     writer.cpp
   HDRS
     writer.h
   DEPENDS
     libc.src.string.memory_utils.memset_implementation
 )
add_object_library(
   DEPENDS
     .parser
     .converter
     .writer
     .core_structs
     libc.src.__support.arg_list
 )
 
+if(NOT (TARGET libc.src.__support.File.file))
+  # Not all platforms have a file implementation. If file is unvailable,
+  # then we must skip all file based printf sections.
+  return()
+endif()
+
+add_object_library(
+  file_writer
+  SRCS
+    file_writer.cpp
+  HDRS
+    file_writer.h
+  DEPENDS
+    libc.src.__support.File.file
+    .core_structs
+)
+
 add_object_library(
   vfprintf_internal
   SRCS
     vfprintf_internal.cpp
   HDRS
     vfprintf_internal.h
   DEPENDS
     libc.include.stdio
     libc.src.__support.File.file
     libc.src.__support.File.platform_file
     libc.src.__support.arg_list
     libc.src.stdio.printf_core.printf_main
     libc.src.stdio.printf_core.file_writer
     libc.src.stdio.printf_core.writer
 )

libc/test/src/stdio/printf_core/parser_test.cpp

TEST(LlvmLibcPrintfParserTest, EvalOneArgWithShortLengthModifier) {
   expected.conv_name = 'd';
 
   ASSERT_FORMAT_EQ(expected, format_arr[0]);
 }
 
 TEST(LlvmLibcPrintfParserTest, EvalOneArgWithLongLengthModifier) {
   __llvm_libc::printf_core::FormatSection format_arr[10];
   const char *str = "%lld";
-  int arg1 = 12345;
+  long long arg1 = 12345;
   evaluate(format_arr, str, arg1);
 
   __llvm_libc::printf_core::FormatSection expected;
   expected.has_conv = true;
   expected.raw_len = 4;
   expected.raw_string = str;
   expected.length_modifier = __llvm_libc::printf_core::LengthModifier::ll;
   expected.conv_val_raw = arg1;
   expected.conv_name = 'd';
 
   ASSERT_FORMAT_EQ(expected, format_arr[0]);
 }
 
 TEST(LlvmLibcPrintfParserTest, EvalOneArgWithAllOptions) {
   __llvm_libc::printf_core::FormatSection format_arr[10];
   const char *str = "% -056.78jd";
-  int arg1 = 12345;
+  intmax_t arg1 = 12345;
   evaluate(format_arr, str, arg1);
 
   __llvm_libc::printf_core::FormatSection expected;
   expected.has_conv = true;
   expected.raw_len = 11;
   expected.raw_string = str;
   expected.flags = static_cast<__llvm_libc::printf_core::FormatFlags>(
       __llvm_libc::printf_core::FormatFlags::LEFT_JUSTIFIED |